Recently one of my scent class students, I’ll call her June, got me thinking a lot about pressure. This article on the application of spatial pressure, whether intentional or inadvertent, and how it affects dog behavior in the context of scent detection tasks is the result of this thought. This article also explores how handlers can avoid pitfalls and use spatial pressure to their advantage.
In scent classes, students learn how to teach their dogs to locate hidden Q-tips dipped in essential or aromatic oils the same way police dogs are taught to locate drugs. This sport can be frustrating for newer handlers because scent detection places demands on handlers to: (1) become close observers of their dog’s natural behavior and (2) learn to use these observations to facilitate a sound search pattern by means of movement and pressure—e.g., body language and handler proximity. Handlers must develop a different focus from what they have been used to in other areas of dog training—possibly for many years—and it can feel uncomfortable to a novice. After all, in most other dog sports, handlers simply direct the dog’s activity, such as asking a dog to heel or having a dog beg for a reward. In scent detection, dogs and handlers work as partners, with handlers reading both their dogs’ behavior and ever-changing environmental factors, while periodically helping their dogs to cover an area using subtle spatial pressure.
For this article, spatial pressure can be defined as the mild emotional discomfort created in another by moving into that person’s—or dog’s—personal space (proximity), as well as the feeling a tight, enclosed space can create, to varying degrees, in a person or dog. This discomfort should not be confused with stressing the dog—the dog should be free to continually release the pressure (or pull) they feel by moving closer or farther from their handler. Both dogs and humans experience this; it is the same effect that causes people to step back from a person who stands a little too close in an elevator. Each person and each dog has a different pressure threshold, and this threshold changes in different environmental contexts. The art of detection is learning to read this behavior and understanding how to use it effectively to complete detection tasks.
In the recent class I mentioned, June had walked away from a location where her dog Rex had detected scent. Because her back was turned, she missed Rex’s behavior. Rex looked back and forth between the scent and June, and then, because of the inadvertent release of pressure caused by her walking away, he left the hidden tin and followed June away from the scent, creating a false negative—you could almost see Rex shrug. June then moved directly toward Rex while he was exploring a cluttered corner, i.e., an enclosed space, which was also squarely in the middle of two overlapping scents. Not surprisingly, she triggered a false indication.
On the next problem, June observed behavior she thought might be related to odor. In response, she hovered close, wanting to help Rex but, unwittingly, she applied too much pressure once again. She slowed her pace and Rex followed suit. As Rex slowed, June increased her focus on him, believing that he was slowing because of the presence of scent. Seconds passed, which surely felt longer to June. Uncertain, she tensed up, which increased Rex’s uncertainty. Mirroring June’s actions—Rex was now fully focused on June, watching her for information—Rex gave yet another false indication, probably in an effort to please and also to cope with the stress he had felt from the subtle cues that pass between dogs and their humans. After all, June’s behavior indicated to Rex that there was something in the vicinity he ought to locate. June was beside herself—thus, piling on still more emotional stress in an activity that is supposed to be fun.
Pressure—physical and mental—is a tricky thing to work with. A little spatial pressure can encourage our dogs to move out and explore a sector (the bounded area designated for a search); whereas, blocking a dog’s path can encourage a dog to remain in one location until they can locate a hidden scent. But spatial pressure is a funny thing. As June learned, spatial pressure can also push our dogs into false alerts or, alternatively, pull them away from source. Utilizing pressure in scent work becomes a sort of dance. When it’s going well, it makes a handler feel totally in sync with their dog. But it is also one of the more difficult skills to learn, and novice handlers often feel like they have the scent detection equivalent of two left feet.
In scent, there is a path marked by an invisible plume of scent that only our dogs can map out. A handler must learn to read subtle cues, the flick of the head, a small lifting of the nose, or a subtle change in breathing, and then think on their feet about whether to apply or release pressure: apply it to support the dog’s location, or release it to give the dog the space needed to explore fully the contours of a scent plume—or even leave an area when there is no scent present. The handler must also determine how much pressure to apply or release in the given circumstances because the environment in which the handler applies pressure or releases it can also have a significant impact on the outcome—it’s more akin to doing threshold work with a reactive dog than it is to other canine sports. Finally, students must learn how to support their dog when the dog is working out a scent plume, without applying too much pressure and thus cuing a false alert, as June did with Rex.
So how can an instructor help a student to develop a feel for the movements involved in generating the pressure, or pressure releases, required to move a dog effectively through a search? Although nothing will replace simply working dogs over time, learning to read their individual behaviors, and getting a feel for how sensitive to pressure the dog is, I thought there must be a way to break down the art of detection-dog handling into learnable components. After reading a study on synchrony (Duranton et al. 2017) —the act of mimicking or mirroring another’s behavior in some way—I realized that this concept, mediated by the concept of spatial pressure, could help break down handling into discrete elements. These elements could then provide students guidance on learning the give-and-take necessary for them and their dogs to develop into a calm, quiet scent detection team.
Synchrony between a dog and human (or what scientists call “interspecific behavioral and locomotor synchrony” [see Duranton et al. 2017, e.g.]) is a technical way of saying that dogs will mirror our behavior. According to scientists, this mirroring happens in at least three different contexts: temporal synchrony, location synchrony, and activity synchrony. As a detection-dog handler and scent-work trainer, I can say that synchrony also interacts with spatial pressure (a mix of proximity, environment, and handler stance—think about how you would feel in a crowded bar versus in an empty warehouse) in ways that can both help us and hurt us when we’re working out a scent problem. Each of the three forms of synchrony shifts our focus to a different factor that can impact detection handling, although each will impact handling differently depending on handler and environmental pressure, to either help or hinder a scent work team.
Synchrony pervades all aspects of life. Night turns to day and we coordinate our behavioral responses by means of internal circadian rhythms. Summer turns to winter and some animals hibernate, while others migrate. There is even coordination between our cells.4 A clapping audience slowly synchronizes into a shared tempo. There are unscripted human waves at football games (Bear et al. 2016). Dolphins swim, jump, and rise to breathe together as a pod. People getting to know one another start to unconsciously reflect each other’s body language as they gain intimacy (Duranton et al. 2016). As animals, we are all governed on multiple levels by synchrony.
Similarly, our dogs synchronize their behavior with that of others. Unlike most other creatures, however, dogs have also learned to synchronize their behavior with us, their human caregivers—thereby forming what is possibly a unique interspecific or interspecies synchrony. Although scientists are still exploring the history of the dog-human bond, it is easy to see why interspecific synchrony between dogs and humans developed. It makes intuitive sense.
Dogs are unusually dependent on their human companions for food, shelter, and companionship. They form close bonds with us. They partner with us at work and protect us from threats. They also exhibit all three forms of synchrony, which probably includes social referencing (Duranton et al. 2016), although social referencing may be more of a conscious choice than the more unconscious process of falling into step with others—i.e., the process of synchrony (Duranton et al. 2017). In essence, it is a good survival strategy for dogs to get into sync with the humans in their lives because synchronization acts to strengthen social bonds and coordinate behavior during shared tasks.5
Because synchrony between dog and human behavior is so strong, people working scent problems with their dogs should understand each type of synchrony and how it interacts with pressure, in order to help their dogs cover an area effectively, without triggering false indications.
Temporal synchrony refers to the timing between handler and dog, and occurs when a handler shifts away from an activity and their dog unconsciously alters their behavior in order to stay in temporal sync with the handler. This does not necessarily mean that the team is engaged in the same behaviors. What is important is the timing. There may also be breed and age differences in how quickly a dog shifts their behavior in response to the handler’s shift—in Duranton et al.’s (2017) study, shepherds exhibited shorter latency than molossoid dogs, and older dogs shifted more quickly than young ones.
Temporal shifts in behavior will always impact a dog’s search behavior, but how a shift affects a search depends upon the amount of pressure that the handler is placing on the dog at the time—how close in space is the handler to their dog? Is the handler facing the dog or standing sideways? Is the handler positioned to walk away? All of these factors will interact with a temporal shift when it occurs, resulting in different outcomes for a dog’s search behavior.
As an example, if the handler is in a wide-open field and the dog is hovering around their feet, and then the handler steps forward suddenly and makes a forward motion with their arms as if to toss something away, the dog is likely to shift their behavior in response. Most likely the dog will shift from hovering and will move away from the handler in the direction of the handler’s forward movement (different types of synchrony work together—here the temporal shift in behavior is interacting with location and activity synchrony as both move forward together). How far the dog goes and for how long will vary depending upon a whole host of dog-specific factors—but you will almost always get at least a small surge of forward movement from the dog, and whether the dog moves forward or not, their behavior will certainly shift in some small way.
Another example is when a handler walks to a spot where scent is hidden and stops, or simply hovers, like June did when working Rex. This is a common practice of novice handlers who are anxious for their dogs to succeed. The dog registers the stop and also stops or slows, mirroring the handler. Often the dog will indicate scent at that spot. This indication is the result of handler pressure combined with the sudden stop, and is not attributable to a commitment to scent.
Temporal synchrony is partially responsible for the behavioral change: The shift in behavior drew the dog’s attention, causing the dog to alter their behavior, but proximity and the pressure it creates is what probably caused the indication. If a team engages in this pattern of stop-and-hover at each suspected scent location, that team will be plagued by false indications because this type of training error creates a dog that is overly focused on the handler—which is why developing an awareness of our behavioral shifts is important, especially when working close to the dog. Novice handlers should try to avoid stopping at all, instead simply slowing or circling an area when they wish to keep their dog at a specific location and focused on work.
So, why is awareness of our behavioral shifts especially important when working close to our dogs? Back in the open field, if the same dog exhibits interest in a location and the handler comes to a stop 100 feet away, the handler’s stop would merely support the dog and encourage them to remain in the vicinity until they targeted the scent or determined that there was nothing there. Here, distance enables the handler to shift their behavior without pressuring the dog into an indication because the synchrony is, in effect, mediated by handler pressure—and in this case the pressure is lower than in the previous example. The dog’s inclination to stay and work an area was honored by the handler. The distance prevented handler pressure from causing a problem; the dog remained free to work independently.
The next form of synchrony, location synchrony, or “being in the same place at the same time,” also impacts scent work, and is also mediated by handler pressure. Basically, dogs will tend to follow their handlers—although how closely they will do so is variable. If a handler walks out into a field, the dog will follow.6 In a room, if a handler walks left, the dog will eventually gravitate left. If the handler goes right, so goes the dog. This tendency is quite helpful to working detection dogs because it means the handler can subtly influence how the dog covers a space without constant and distracting verbal commands, which can hinder a dog from the job or even call the dog off the scent they were asked to locate.
The handler can use pressure in conjunction with location synchrony to regulate how quickly the dog is likely to synchronize their location to that of the handler. If a handler turns away from the dog and walks off quickly, most dogs will follow fairly rapidly—a good strategy for getting a dog past a potent distraction without having to yell “leave it” or, worse, physically pull the dog away. If the same handler backs slowly away from the dog, the forward pressure (from the handler facing the dog as they back away) will allow the dog to follow more slowly, giving the dog time to clear the area for scent before following the handler’s path. By facing the dog and moving laterally left or right, a handler can move their dog laterally without encouraging the dog to diminish the actual distance—which is a good thing, because greater distances mean less pressure on the dog (fewer false alerts), and the handler can better see the full spectrum of the dog’s behavior from a distance and whether the dog is exhibiting any interest in a specific location.
Finally, there is activity synchrony, contemporaneously engaging in the same behavior. Again, this can help or hinder a search team, and again pressure mediates its effect. With novice handlers you see activity synchrony hindering teams most frequently when handlers become uncertain or slow, tense up, or hesitate, as June did when trying to help Rex. As Rex did, dogs will also slow, become uncertain, focus excessively on the handler, or even offer a wishful indication without exhibiting any focused nose work. When training a handler, giving them a task to focus on, such as telling them to ignore their dog and act like they’re looking for a lost item, is often all that it takes to get the dog searching again—using activity synchrony this time to assist the team. This shouldn’t surprise us since science has shown that dogs can learn tasks by watching people, and that they even engage in social referencing, such as learning how to react to a stranger by watching the handler (Duranton et al. 2016).
Another way that activity synchrony can create a problem for new handlers is seen when handlers focus on their dog rather than the task, and also when handlers move stiffly, creating the impression that they are engaging in obedience training. In the first example, handlers stare at their dogs and the dogs stop searching and stare back. This is especially problematic when a dog has been formally trained to offer eye contact. Dogs with a strong reinforcement history for eye contact may require more preconditioning—classically conditioning a dog to associate a scent with a reward prior to starting actual search work—than the average dog to get their focus off their handlers and onto the detection task. Or the dogs may benefit from a helper or instructor counter-cueing them (having a person other than the handler draw the dog’s focus to the scent).
In the second example, handlers may walk stiffly, holding a military-like posture, or maybe they have practiced heeling for so long that they lift their hand to their stomach subconsciously. Their dogs will usually forget about looking for scent and fall quickly into heel position, focusing wholly on their handlers. Normally all that is needed is to ask handlers to look at the search containers; this will usually get the dogs back on task—research documents how dogs will gaze where the handler gazes more frequently than elsewhere (Duranton et al. 2017). Teglas et al. (2012) even suggest that the tendency of dogs to follow gazes is a “functionally infant-analog social competence.”
Dogs taught to offer eye contact may have a harder time learning to follow their humans’ gaze (Wallis et al. 2015), but it is not just dogs with obedience training that have trouble learning to roam freely, think independently, and explore—and it is not just obedience trainers who unthinkingly give cues to which their dogs are primed to respond. Activity synchrony can hinder teams without a lot of prior training too (Duranton et al. 2018). Dogs know when we are communicating with them, certainly if we are trying to, but even when our message is sent on an unconscious level through subtle physical cues (e.g., the “Clever Hans” effect).
I had a student who initially would walk her dog directly to the source—she swore she wasn’t! I finally got her to stop walking over, but she replaced this behavior with unconsciously pointing her dog in the direction of the source before releasing him to search. She was frustrated when I told her what she was doing, but gamely altered her behavior. Despite the change, it still looked to me like the dog was being directed to the source, but how? Then I saw it. She was glancing at the scent’s location before she even entered the ring and set up her dog to search—she looked quickly at the hidden source, and so her dog looked too, and then they walked in, ready to search. This woman and her dog were wonderfully in sync with one another, but it was not a good recipe for when the team would start working on blind hides, where the handler does not know the location of the scent—fortunately, she was able to stop even glancing at a hide and ended up doing well. But this example illustrates how easy it is for synchrony to undermine detection teams, even though it may help them in other settings.
In the context of activity synchrony, pressure simply increases or decreases the saliency of the handlers’ behavior. Staring at a dog working a couple hundred feet away is not going to trigger activity synchrony, although that same dog may be unable to drop his gaze if the handler stared at him from a foot or two away. An abrupt absence of pressure (or pull) that can occur when a handler walks away fast, however, may draw the dog quickly to mirror the handler’s path, even at a greater distance.
Dogs are social animals. Most dogs thrive on working with their handlers and, for the most part, pleasing them. Using synchronies, while maintaining an awareness of proximity and pressure, facilitates a closer relationship. Less chatter increases focus on task and confidence. Using fewer commands fosters mutual respect and supports greater independence and joy in dogs, while reducing false positives and negatives. Understanding our dogs’ tendency to synchronize with humans and using this tendency to a team’s advantage will increase and strengthen this predisposition over time, until that team can move through their detection task as if silently communicating throughout. Detection is teamwork; synchrony is the oil that keeps partners working together smoothly.
This article has dissected different types of synchrony and pressure and placed them into discrete categories, but the real world is messier and many factors interweave into one another throughout a search. The environment is also constantly shifting how pressure and synchrony operates. Outdoors is different from indoors, and a playroom is different from a closet. All this needs to be considered when determining how easy it might be to increase or release pressure, or get a dog to follow our movement or the direction of our gaze. The main thing is to start paying attention; observe how, in silence, you and your dog can partner as you move through a search area and slowly develop from being “a dog” and “a handler” into a solid detection team.
Duranton, C., Bedossa, T, and Gaunet, F. (2016). When facing an unfamiliar person, pet dogs present social referencing based on their owner’s direction of movement alone. Animal Behavior 113, pp. 147-156.
Kathryn Gordon MSW, CPDT-KA, has trained and handled search and rescue dogs, primarily in the area of human remains detection, since 2011. She currently owns OnScent L.L.C., a business that offers group and private classes in scent detection and basic obedience, as well as working with clients to resolve a variety of behavioral issues. Kathryn’s training philosophy centers on building a dog’s confidence and independence through positive, choice-based training. She spends her free time working and playing with Hexi, a German shepherd, and Gus, a rescued border collie, both certified land-cadaver and crime-scene detection dogs.
 I believe that this aspect of scent detection, partnering versus commanding, when done correctly, helps to improve the relationship between a dog and the handler. Further, having freedom to explore an area and problem solve independently increases the dog’s confidence. Together, these effects explain much of why scent detection has become so popular as a sport.
 Scent sources release molecules into the air that move via convection, usually vertical movement, and advection, usually horizontal movement, forming scent plumes that may in some instances slowly expand in space (leading some to erroneously refer to them as cones) as the molecules decrease in concentration as they travel over distance. (For an exhaustive description of convection and advection see Cussler (2009) and Parker (2003).) When two sources are placed relatively close to one another, the two plumes of scent can overlap, creating an area of high scent density (referring to a high count of scent molecules in a given volume) that is not close to either source. This overlap can cause inexperienced dogs to indicate. For a broad overview of scent plumes see Vickers (2000).
 In scent detection, indications that are not as close to source as reasonably possible are deemed false—there is also a grey area where an indication is deemed “on the fringe.” The dog may be reacting to scent, but has failed to persevere until locating the actual source of the scent.
‘\ Electrical rhythms in the cerebral cortex can reach amplitudes detectable by an EEG when responsibility for the cells’ task is distributed and coordination is shared.
 E.g., Protopopova and Wynne (2014) found that the only variables predictive of whether an adopter would adopt a particular dog or not were a refusal to accept an invitation to play, i.e., activity synchrony, or the lack of it, and lying at the adopter’s feet, i.e., location and possibly activity synchrony.
 See Duranton, et al. (2018) discussing pet dog location and activity synchrony in an outdoor setting.